ISSN print edition: 0366-6352 ISSN electronic edition: 1336-9075 Registr. No.: MK SR 9/7 Published monthly

Interpretation of the wetting contact-angle in the system various coal ranks-liquid drop-air

T. Bialopiotrowicz, B. Jańczuk, and W. Wójcik

Department of Physical Chemistry, Institute of Chemistry, Maria Curie-Sklodowska University, PL-20-031 Lublin

Abstract: Measurements of the contact angle in the systems various coal ranks—water drop—air and various coal ranks—methylene iodide drop—air were carried out. Then, for the systems studied an analysis of the equilibrium state was made on the basis of the modified Young equation (taking into account all possible factors influencing the contact angle). We have found that the surface Gibbs energy of various coal ranks results from both dispersive and nondispersive intermolecular interactions and its value depends on the coal rank. It was also stated that the surface of coal is heterogeneous, which leads to the differences of the contact angle values for a given coal rank. These differences were smaller for higher coal ranks. The calculations carried out suggest that the existence of water film on the coal surface does not only change its surface Gibbs energy but also the ratio of the dispersion values to those of the nondispersion components.

Full paper in Portable Document Format: 425a577.pdf

Chemical Papers 42 (5) 577–587 (1988)